In recent electronic devices, resin is commonly used as a material of a main housing body. Although less expensive than metal, resin used as a material of a main housing body is lower in thermal conductivity than metal. Therefore, in many electronic devices, vent holes are formed on an outer surface of the main housing body and ventilation is performed between an inner part and an outer part of the main housing body through the vent holes to cool the inner part of the main housing body (see, for example, Patent Literatures 1 and 2).